Method of forming contact tapes



C. C. VEALE METHOD OF FORMING CONTACT TAPES March 18, 1958 Filed May 6, 1954' INVENTOA A TTOR/Vfy I FIG. 7

METHOD or FonMrNo CONTACT TAPES Charles C. Veale, West Chicago, 111., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application May 6, 1954, Serial No. 427,947

'1 Claim. (Cl. 80-60) This invention relates to a method of forming contact tapes and more particularly to a method of rolling a round wire of contact material into a tape having a predetermined isosceles trapezoidal cross section.

Contact tape of trapezoidal cross section, according to one method of manufacture followed heretofore, was formed from a round wire by passing the wire through a single pair of forming rolls having cooperating annular surfaces defining a tape forming opening of the desired trapezoidal outline. However, since it is ditficult to maintain the round wire in perfect central alignment with the trapezoidal opening of the rolls, the tape produced thereby frequently had flanges formed thereon along one side edge or the other as the result of slight misalignment of the wire during rolling of the tape. The side flanges formed on the tapes render them undesirable and unsatisfactory in that, among other things, such tapes are diflicult to guide into precise predetermined operative positions during subsequent processing thereof.

An object of the present invention is to provide a method of forming contact tape having a uniform cross section of isosceles trapezoidal configuration.

A further object of the invention is to provide an improved method of rolling bi-laterally symmetrical contact tape from a wire of contact material.

A method illustrating certain features of the invention for forming contact tape of a predetermined isosceles trapezoidal cross section may include passing a round wire of contact material between a first pair of driven forming rolls having cooperating annular surfaces defining a triangular tape forming opening to cause the forming surfaces thereof to engage three sides of said wire and press successive portions longitudinally thereof to form a triangular tape having an isosceles triangular cross section with the base face thereof having a width equal to that of the narrower one of the parallel faces of said predetermined trapezoidal tape, and passing said triangular tape through a second pair of driven forming rolls having cooperating annular surfaces defining a tape forming opening of said predetermined trapezoidal shape and with the base face of the triangular tape in engagement with the narrow one of the parallel sides of the tape forming opening to cause the apex of the triangular tape to be pressed toward and deformed relative to said base face to form a tape of said predetermined trapezoidal cross section.

Other objects and advantages of the invention will become apparent by reference to the following detailed description and the accompanying drawings illustrating a preferred embodiment thereof, in which Fig. l is a diagrammatic side elevational view of a portion of the tape forming apparatus;

Fig. 2 is an enlarged fragmentary perspective view of a portion of a round wire from which the contact tape is to be formed;

Fig. 3 is an enlarged fragmentary perspective view of the triangular shape of the wire after it has passed through the first pair of forming rolls;

Fig. 4 is an enlarged fragmentary perspective view of the contact tape after it has passed through the second pair of forming rolls;

Fig. 5 is a fragmentary enlarged cross-sectional view through one of the first pair of forming rolls taken on the line 55 of Fig. l and showing the wire lying in the groove of the roll;

Fig. 6 is a fragmentary enlarged cross-sectional view through the first pair of forming rolls taken on the line 6--6 of Fig. 1 and showing the triangular tape formed thereby; and 5 Fig. 7 is an enlarged fragmentary view showing the sec ond pair of forming rolls and the finished tape formed thereby. 1

The present method relates to the forming of a contact tape 10 having an isosceles trapezoidal cross-sectional configuration with upper and lower parallel faces 11 and i2 and a pair of side faces 13 and 14 sloping downwardly and outwardly from the upper face 11 and with a welding head 15' formed along the center of the lower face 12. It is an important feature of the invention to form the tape so that it is bi-laterally symmetrical and so that it has no laterally extending flanges formed thereon.

A round wire 17 of contact material is passed through a pair of driven forming rolls 2t and 21, the upper roll 21 having an annular V-shaped groove 22 therein which cooperates with the cylindrical periphery of the roll 21 to define a tape forming opening 23 of an isosceles triangular outline to engage the wire at three points and press it into a triangular tape 24 of predetermined size. The corners of the tape 24 are rounded and have relatively small radii of the same size as the corners formed by the faces ll, 13 and 11, 14 of the tape 10, and the sides of the tape form an isosceles triangle with the bottom face or base 25 thereof equal in length to the width of the face 11 of the contact tape it). Thus, the face 11 with its curved edges of the finished contact tape 10 is formed on the tape 24 during its first pass through the rolls 20 and 21. To facilitate the rolling of the wire 17 into the triangular tape 24 the wire is wrapped around the upper roll Zn in engagement with the groove 22 therein, is guided around an idler, and is drawn through a sizing die 26 from a source of supply (not shown). The triangular tape 24 may be wound on a spool for subsequent processing into the trapezoidal contact tape 10.

The triangular tape 24 is inverted with the face 11 disposed uppermost and is then passed through a pair of driven forming rolls 3t? and 31 which compress the tape 24 and form it into the desired trapezoidal shape. The tape 24 is guided into engagement with the rolls by a suitable guide or guill (not shown). The upper forming roll 39 has an annular groove 32 formed therein comprising a cylindrical surface 33 which has a width corresponding to the width of the face 11 of the contact tape it? and against which the face 25 of the triangular contact tape 24 is adapted to engage during the second pass. A pair of conical surfaces 34 slope from the cylindrical surface 33 to the outer peripheral cylindrical surface 35 of the roll 3 The conical surfaces 34 serve to engage the corners of the tape 24 on opposite sides of the face and accurately align the tape centrally of the groove 32 in the roller 3i? and also to confine the metal of the tape as it flows laterally during the second pass to form the sloping sides 13 and 14 on the tape It). The cylindrical periphery of the roll 31 forms the bottom face 12 of the tape in parallel relation to the upper face 11 and a centrally disposed annular groove 37 in the cylindrical periphery of the roller 31 engages a corner of the triangular tape 24 and forms the central head 15 on the contact tape it).

As the inverted triangular tape 24 is passed through Patented Mar. 18, 1958 the trapezoidal opening formed between the cooperating rolls 30, 31, the apex of the triangular tape 24 is squeezed by the roll 31 toward the face 25 of the tape 24 and against the roll 30, causing portions of the metal to flow relative to the face 25 laterally into engagement with the conical surfaces34 and with the cylindrical surface of the forming roll 31 and be formed thereby into the Plfi", determined trapezoidal configuration as shown in Fig. 7.

The contour and size of the opposite corners 40 which are the last portions of the tape to be formed, may vary slightly according to variations in cross-sectional area of the tape within a narrow range of allowable manufacturing tolerances and according to slight allowable variations in hardness. However, each of the corners 40 on a tape are of the same size and of reverse shape so that contact tapes made according to this method are bi-laterall'y symmetrical, of uniform size, and vary slightly only in the contour of the corners 40.

It is to be understood that the above-described arrangements are simply, illustrative of the application of the principles of this invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

A method of forming contact tape having a trapezoidal cross section comprising forming a circular wire into a tape having a triangular cross section consisting of a base side of predetermined width and a predetermined apex angle between the other two sides, and applying forming pressure to the apex and the two sides that diverge therefrom to flatten the material of the tape to form a surface that is parallel to and extends beyond the ends of the base side of the tape and confining the material of the base side against lateral displacement while applying the forming pressure to the two sides of the triangular tape material whereby the resulting tape is trapezoidal in cross-sectional shape.

References Cited in the file of this patent UNITED STATES PATENTS 652,709 Baker June 26, 1900 1,154,664 Slick Sept. 28, 1915 2,150,416 Cairns Mar. 14, 1939 2,160,268 Hunter May 30, 1939 2,316,067 Hickman Apr. 6, 1943 2,643,559 Scheuerman June 30, 1953 

